Hi, Sergei, Georg, Please review a fixed version of the patch for MDEV-17832. There are two files attached: - mdev-17821.v18.diff (server changes) - mdev-17821-cli.v06.diff (libmariadb changes) Comparing to the previous version, this version: 1. Adds a new structure MA_FIELD_EXTENSION 2. Moves extended data type information from MYSQL_FIELD to MYSQL_FIELD::extension in the client-server implementation. Note, in case of embedded server, the extended metadata is stored directly to MYSQL_FIELD. 3. Adds a new API function mariadb_field_metadata_attr(), to extract metadata from MYSQL_FIELD. 4. Changes the way how the metadata is packed on the wire from "easily human readable" to "easily parse-able", which: - makes the things faster - allows to transfer arbitrary binary data in the future, if needed. Every metadata chunk is now encoded as: a. chunk type (1 byte) b. chunk data length (1 byte) c. chunk data (according to #b) For now, two chunk types are implemented: - data type name (used for GEOMETRY sub-types, and for INET6) - format name (for JSON) Thanks!